With the ever expanding frontiers of space and aviation, and with modern aircraft now operating at altitudes which only a few decades ago were thought to be impossible, it is becoming increasingly important to overcome some problems introduced by high altitude flight. At high altitudes, the ambient light is often quite bright and may adversely affect the performance of optical avionics equipment.
One particular type of avionics equipment in which high ambient light is posing vexing problems is liquid crystal displays. Basically, back lighted LCD's utilize a back light to generate a white light which is filtered by a liquid crystal filter to create an image. The back light is frequently an incandescent or fluorescent lamp which typically have bright spots therein. The bright spots have been attenuated, in the past, by placing light absorbing dots on the lamp side of a diffuser placed between the lamp and the liquid crystal filter.
While this design, or variations of it, have enjoyed significant use in the past, it does have several serious drawbacks. A major drawback with the light absorptive dots placed on the lamp side of the diffuser is that it causes an overall reduction in the brightness of the liquid crystal display panel. Another problem with such a design is, the absorptive dots typically absorb heat, as well as light, and thereby create a panel with a higher overall operating temperature.
Consequently, there exists a need for an improvement and advancements in the design of liquid crystal display panels which provide for a uniform brightness across the liquid crystal panel with a concomitant increase in overall panel brightness, without any increase in lamp power or operating temperature.